The present invention relates to a duplex type coating apparatus capable of simultaneously coating both faces of a web of cloth, plastic film, metal sheet, or glass plate, which are in an elongated shape, or a metal sheet in a net-like shape, a porous metal sheet or the like with a coating solution.
Recently, with the increased use of portable telephones and portable information terminals, mass production of lithium cells of a spiral electrode type has been actively carried out. Further, it is necessary in mass production of the lithium cells to carry out so-called intermittent coating in which coated portions and uncoated portions are alternately formed on strip-like hoop material (that is, a web) of a copper foil or an aluminum foil in a length direction of the web by a slurry clad material (that is, a coating solution) composed mainly of an electrode activating substance and further, it is necessary to coat the coating solution at the same position on both faces of the web.
Hence, the applicant has previously proposed a coating apparatus capable of coating a coating solution on both faces of a web (Japanese Unexamined Patent Publication No. JP-A-8-206567). The coating apparatus is installed with a pair of dies on both sides of a transfer path of a web. A solution reservoir for the coating solution and an ejection port for the coating solution are provided in the die and the coating solution is coated on both faces of the web from the ejection ports by supplying the coating solution to the reservoirs. In this case, the ejection port is formed by a fixed lip portion and a movable lip portion and the movable lip portion is arranged to be movable in the up and down direction by an air cylinder by which the ejection port can be opened or closed.
When the intermittent coating is carried out by the coating apparatus, the web is moved along the transfer path and the coating solution is ejected from the pair of dies. Further, when a coated portion is to be formed, the ejection port is brought into a state of being opened by moving the movable lip portion to thereby eject the coating solution. When an uncoated portion is to be formed, the ejection port is brought into a state of being closed by moving the movable lip portion using the air cylinder. Thereby, the coating solution does not come out from the ejection port and therefore, the uncoated portions can be formed on the both faces of the web.
The above-described coating apparatus is provided with a structure in which the movable lip portion is operated by the air cylinder and therefore, there is a problem in that the response time of the operation of the movable lip portion is limited and an interval between the uncoated portions or the coated portions cannot be reduced to less than a certain amount.
Further, as shown by FIG. 17, when coated portions 7a, and uncoated portions 7b are alternately formed on a web 7, there causes a phenomenon in which an amount of a coating solution that is larger than that of other portion is coated and the coated portion is swollen at a position 7d of the coated portion 7a where the coating is started and a position 7e thereof where the coating is finished.